Choosing the Right Hydrogen Storage Solution

Deciding which option is best for your needs depends on several factors, including capacity, cost efficiency, safety, durability, and technical specifications.

Across the industry, Type 4 composite cylinders are increasingly replacing Type 1 steel tube trailers. Their advanced construction, higher efficiency, and lower total cost of ownership are driving this shift. At Hexagon Purus, we are often asked to outline the technical differences.

1. Understanding the Different Cylinder Types

Hydrogen cylinders vary by material and design, with three common types:

• All-steel cylinders (Type 1): Made entirely of steel, these are heavy and can only handle lower pressures (typically up to 200–250 bar).

• Steel cylinders with carbon-fiber wrapping (Type 3): These have a metal liner reinforced with carbon-fiber wrapping to increase strength and pressure tolerance.

• Polymer-lined composite cylinders (Type 4): These are built with a polymer liner on the inside, wrapped with high-strength carbon fiber combined with resin.

Hexagon Purus makes Type 4 cylinders, which have a polymer liner on the inside. We wrap the cylinder with high-strength carbon fiber, combined with resin, to create a very robust material. This construction allows the cylinder to handle very high pressures, up to 700 bar.

Hydrogen weighs almost nothing but takes up a lot of space, so to store a lot of it, you need to compress it into a tank that can withstand immense pressure. For a steel tank to handle 700 bar, the steel walls must be very thick and heavy. In contrast, our Type 4 tanks are lightweight yet incredibly robust, making them ideal for transport applications where weight limits on roads are a critical factor.

How Much Hydrogen Can Each System Carry?

Capacity is a major differentiator between Type 4 and Type 1 systems.

For example, a Type 1 steel tube trailer typically carries around 300–400 kg of hydrogen at pressures of 200–250 bar. In contrast, a Type 4 composite trailer can transport 800–1,200 kg or more at pressures of 350–700 bar.

A steel cylinder capable of storing hydrogen at 700 bar would require extremely thick, heavy steel walls to withstand the pressure, increasing the cylinder’s weight significantly and reducing its efficiency for transport applications.

In contrast, Type 4 cylinders are lightweight yet robust. Their advanced materials allow them to store three times more hydrogen than steel cylinders of equivalent size. This advantage is particularly important in transport applications, where vehicle weight limits and fuel efficiency are critical.

While Type 1 steel trailers may have lower upfront costs, their heavy weight, lower capacity, and susceptibility to corrosion make them more expensive to operate and maintain over time.

Type 4 cylinders are becoming the preferred alternative due to their long-term savings from:

• Improved fuel efficiency: Lightweight trailers consume less energy during transport.

• Less maintenance: Composite materials are highly durable and require little upkeep.

• Longer service life: Many Type 4 systems are rated for 20+ years of use.

For situations where you’re hydrogen is being moved on vehicles or within a distribution system, weight becomes a critical factor. With Type 4 cylinders, you can transport significantly more hydrogen per trip, reducing the number of journeys required and lowering operational costs. Even though the upfront cost of Type 4 systems is higher than steel cylinders, their ability to handle three times the capacity makes them a more economical option over time.

Safety is a key consideration in hydrogen storage, and Type 4 systems excel in this area. The composite construction of Type 4 cylinders allows them to withstand much higher pressures—up to 700 bar—without compromising structural integrity.

Steel tubes in Type 1 systems, while sturdy, are heavier and more prone to degradation over time, especially in corrosive or high-humidity environments. This can lead to safety concerns if proper maintenance isn’t performed regularly.

In contrast, Type 4 cylinders are designed with a polymer liner that prevents hydrogen permeation and a carbon-fiber overwrap that resists impact and pressure-related stresses, making them a reliable choice for high-pressure hydrogen storage.

When deciding between Type 4 cylinders and Type 1 steel trailers, consider your specific needs:

• Do you require high-capacity storage and transport? Type 4 cylinders can carry more hydrogen per trip, reducing operational costs.

• Are you focused on long-term savings? Type 4 systems offer a lower TCO thanks to their durability and efficiency.

• Is safety a top priority? With higher pressure ratings and corrosion resistance, Type 4 systems are the safer choice.